![Sample our Environment & Agriculture journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5934/TOC-Subject-Sample-2021-Environment-Agriculture.jpg"})
Abstract
The ability of two Fusarium oxysporum f. sp. cepae isolates, FOC6 and FOC8, to colonize onion seedlings, following seed inoculation of different cultivars, and the associated quantitative and qualitative polygalacturonase and pectin lyase production were analysed. Allium cepa ‘Akgün 12’ and ‘Rossa Savonese’ were shown to be resistant to both isolates. FOC6 and FOC8 differed in pectolytic enzyme production, isoenzyme patterns, and aggressiveness. The pectolytic enzyme production from FOC6 was generally lower than that of the more aggressive FOC8 isolate. Polygalacturonase activity was correlated with the disease development upon infection with FOC8. Germinating seeds of onion cultivars inoculated with both FOC6 and FOC8 were extracted and fractionated by thin-layer chromatography to determine their content of antifungal compounds. Extracts from resistant cultivars were characterized by the expression of peculiar antifungal fractions, which may be involved in resistance to the pathogen. Results from the present study suggest that, for each cultivar–isolate interaction, the disease severity during onion colonization by F. oxysporum f. sp. cepae is the result of concomitant factors including: (i) the ability of F. oxysporum f. sp. cepae to produce different amounts of pectolytic enzymes, (ii) the production of distinctive pectolytic isoenzyme patterns, and (iii) the expression of distinct antifungal compounds.
